He is the main character. He has a strange ability to change into a girl at night. So there are many problems because of this.
Haruki is Konatsu's boyfriend; Haruki is on the basketball team and Konatsu is the manager. At night Haruki turns into a perverted girl that always makes moves on Konatsu; Konatsu also has problems with her feelings when it comes to Haruki and Haruna.
Haruki's siblings, Ryou and Megumi also switch genders at night.